The production or recycling of nuclear fuel leads to the production of by-products, waste or effluent. It must be verified that the content of radioactive materials in these by-products, waste and effluent is acceptable with regard to regulatory thresholds.
For example, uranium oxide (UxOy) and in particular uranium dioxide (UO2) is used as nuclear fuel. Uranium oxide is obtained for example by conversion of uranium hexafluoride (UF6) to uranium oxide. Conversion is conducted in a furnace for example by counter-current circulation of a powder of uranium hexafluoride and water (H2O). Said manufacturing process is described in FR 2 771 725.
This conversion generates hydrofluoric acid (HF) as recyclable by-product. It must be controlled that the concentration of uranium in the hydrofluoric acid does not exceed the regulatory thresholds laid down by the nuclear safety agency.
To do so, it is possible regularly to take samples and to have them analysed by a laboratory, for example using mass spectrometers, molecular absorption spectrophotometers . . . .
Nevertheless, such analyses require the use by qualified personnel of sophisticated laboratory equipment that is costly to purchase, maintain and operate. They require a time possibly varying from several tens of minutes to a day depending on the necessary preparations and the type of measurement to be performed. They are conducted at regular time intervals but spaced apart. These analyses are ill-adapted to the monitoring of a continuous industrial process and in this case necessitate intermediate storage and treatment in batches at certain steps of the industrial process.